1. Field of the Invention
The present invention relates to a polyurethane composition which is stabilized to light-induced embrittlement and to discoloration or change caused by combustion gas as well as atmospheric conditions, and is improved in dyeability. In addition, the composition retains these high performance characteristics against treatments as such end-product processing, dyeing, commercial dry cleaning, and the like. Accordingly, the present composition is utilizable for a wide variety of polyurethane articles including elastic foams, elastic fibers, synthetic leather, etc.
2. Description of the Prior Art
Japanese Patent Publication No. 6510/72 discloses that a phenolic compound having a specific constitution and molecular weight acts as an antioxidant for polyurethane, depresses the coloration thereof caused by smoggy air, and is scarcely extractable from polyurethane fibers with perchloroethylene, a commercial dry cleaning solvent. Japanese Patent Publication No. 48895/72 also discloses that polyurethane compositions, not only improved in dyeability but which are also markedly stabilized against the yellowing caused by ultraviolet rays or by harmful gas, can be obtained by incorporating a stabilizer polyurethane which contains a restricted tertiary amine structure having a specific constitution and molecular weight. Moreover, Japanese Patent Application Laid-Open Nos. 221355/84 and 223751/84 disclose that polyurethane compositions markedly improved in dyeability and in gas resistance can be obtained by incorporating a stabilizer polyurethane which contains a tertiary amine structure different from the above having a specific constitution and molecular weight with a specific terminal structure. The light stability of these compositions can be improved synergistically by joint use of an antioxidant and a light stabilizer.
In any of these prior art compositions, a polymer having the repeating unit of a low molecular compound is used as a stabilizer. The molecular weight of the polymeric stabilizer is defined but it is an average value, that is, the stabilizer has some molecular weight distribution. Accordingly, these stabilizers contain low-molecular fractions which, during the fiber making process, are liable to bleed out on the fiber surface and form scum. In addition, the low-molecular fractions tend to be lost during the processing or dry cleaning of the fibers. The stabilizers also contain high molecular fractions which have poor stabilizing effects. Even when the stabilizer of the most desirable average molecular weight is chosen, it is inevitable that the stability of the polyurethane fibers is remarkably lowered by subjecting them to processing, for example, dyeing under common conditions of pH 4 and a temperature near to 100.degree. C. or commercial dry cleaning.
Consequently there is still a strong demand for an excellent polyurethane composition and stabilizer therefor that can solve these problems.